OBJECTIVE Untreated girls with Turner syndrome (TS) have short stature, relatively broad shoulders, a broad pelvis, short legs, a high fat mass and low muscle mass. Our objective was to assess the effect of the weak androgen oxandrolone (Ox) on body proportions and composition in growth hormone (GH)-treated girls with TS. METHODS 133 patients were included in a randomized, placebo-controlled, double-blind study. METHODS Patients were treated with GH (1.33 mg/m(2) per day) from baseline, combined with placebo (Pl) or Ox in a low (0.03 mg/kg per day) or previously conventional (0.06 mg/kg per day) dose from the age of eight, and oestrogens from the age of twelve. Sitting height, biacromial and biiliacal distances compared with height (i.e. shape values), BMI, waist circumference, sum of 4 skinfolds (sum4skin) and upper arm muscle area (UAMA) SD scores (SDS) were assessed half-yearly. RESULTS Compared with GH + Pl, adult shape values on GH + Ox tended to be higher for sitting height (Ox 0.03, P = 0.2; Ox 0.06, P = 0.02) and biacromial distance (Ox 0.03, P = 0.2; Ox 0.06, P = 0.07) and lower for biiliacal distance (Ox 0.03, P = 0.004; Ox 0.06, P = 0.08). Sum4skin SDS tended to decrease more (Ox 0.03, P = 0.2; Ox 0.06, P = 0.005) while UAMA SDS increased more (Ox 0.03, P < 0.001; Ox 0.06, P < 0.001) than on GH + Pl. The increase in BMI and waist circumference SDS was comparable between the dosage groups. CONCLUSIONS In GH-treated girls with TS, Ox 0.06 increases sitting height and tends to increase biacromial distance and decrease biiliacal distance, while Ox 0.03 significantly decreases biiliacal distance compared with height. Furthermore, Ox 0.06 reduces subcutaneous fat mass, and both Ox dosages increase muscle mass.